Hybrid Radar Antenna Array for Sparse-Receive Aliasing Control
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Solution Overview
Problem
Traditional phased-array radar systems are unsuitable for applications like autonomous vehicles and drones due to their size, power requirements, high element density, cost, and limited Rayleigh resolution, which is constrained by the number of antenna channels, leading to trade-offs between field of view and resolution.
Innovation Solution
The radar system employs an analog transmit array for electronic beam steering and spatial filtering, combined with a sparse digital beam-forming receive array, allowing for narrow beam widths without the need for a large number of antenna channels, effectively reducing aliasing and improving angular performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional phased-array radar system uses a dense antenna array to achieve narrow beam width and high Rayleigh resolution, then the angular resolution is improved, but the system becomes too heavy, power-hungry, expensive, and complex for applications like autonomous vehicles and drones
Solution Approach 1:
The antenna array is divided into multiple subarrays, where each subarray is independently controlled to form a beam. This segmentation allows the system to achieve high angular resolution with fewer total elements by coordinating the phase and amplitude across subarrays, thereby reducing overall system complexity while maintaining measurement precision.
Solution Approach 2:
The patent transitions from a two-dimensional dense array to a three-dimensional sparse array configuration. By adding the vertical dimension and strategically positioning elements in 3D space, the system achieves high Rayleigh resolution without requiring dense packing in any single plane, thus reducing device complexity and element density requirements.
2Measurement precision
If the number of antenna channels is increased to improve Rayleigh resolution, then the angular performance is enhanced, but the system cost, power consumption, and complexity increase
Solution Approach 1:
The antenna array is divided into multiple subarrays, where each subarray is independently controlled to form a beam. This segmentation allows the system to achieve high angular resolution with fewer total elements by coordinating the phase and amplitude across subarrays, thereby reducing overall system complexity while maintaining measurement precision.
Solution Approach 2:
Each antenna element is designed to serve multiple functions: it participates in forming multiple different beams across various subarrays and scanning positions. This multi-functionality allows the system to achieve high Rayleigh resolution with fewer channels, as each channel contributes to multiple beamforming operations rather than being dedicated to a single function.
3Device complexity
If a sparse antenna array is used to reduce the number of channels and lower system complexity, then device complexity is reduced, but spatial aliasing occurs which produces side-lobes and grating lobes that hinder object detection
Solution Approach 1:
The system pre-calculates and stores complex weights for each subarray and scanning position before actual beamforming operation. This preliminary preparation allows the sparse array to correctly form beams without spatial aliasing during real-time operation, as the optimal weighting coefficients are determined in advance to account for the sparse geometry and prevent grating lobes.
Solution Approach 2:
The patent dynamically adjusts the complex weights (amplitude and phase parameters) assigned to each antenna element based on the desired beam direction and subarray configuration. By changing these parameters adaptively, the system compensates for the sparse array geometry and eliminates spatial aliasing effects, allowing low complexity to coexist with high performance.
4Area of stationary object
If the field of view is widened to cover more area, then the coverage is improved, but the Rayleigh resolution deteriorates due to the fixed number of receive channels
Solution Approach 1:
The antenna array is divided into multiple subarrays, where each subarray is independently controlled to form a beam. This segmentation allows the system to achieve high angular resolution with fewer total elements by coordinating the phase and amplitude across subarrays, thereby reducing overall system complexity while maintaining measurement precision.
Solution Approach 2:
The patent transitions from a two-dimensional dense array to a three-dimensional sparse array configuration. By adding the vertical dimension and strategically positioning elements in 3D space, the system achieves high Rayleigh resolution without requiring dense packing in any single plane, thus reducing device complexity and element density requirements.
Data Source
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AI summary
In an embodiment, an antenna subsystem includes a sparse receive antenna and an electronically steerable transmit antenna. The sparse receive antenna includes an array of receive elements each configured to receive a respective signal having a wavelength and each spaced apart from each adjacent one of the receive elements by a respective first distance that is more than one half of the wavelength. And the electronically steerable transmit antenna includes an array of transmit elements each configured to radiate a respective signal having the wavelength and each spaced apart from each adjacent one of the transmit elements by a respective second distance that is less than one half of the wavelength. To reduce aliasing, such an antenna subsystem can be operated to filter, spatially, a receive beam pattern generated by the receive antenna with a transmit beam pattern generated by the transmit antenna.